Roadside signs have long been effective means for advertising and conveying messages. Known billboard style signs are advantageous in that they successfully advertise a message to a broad audience for a relatively low price. However, these signs suffer from a severe disadvantage in that their display message may be posted for weeks or months limiting their effectiveness over the long term. The viewing audience simply becomes bored with the same inanimate sign displaying the same message, and its marketing effectiveness drops off significantly over time.
In response to conventional forms of billboard advertising, multi-sided, segmented, rotating signs were developed. These signs typically comprise a number of three-sided sign segments driven by a motor that selectively starts and stops or by a motor having some type of trip mechanism or clutch. One example of this type of sign is disclosed in U.S. Pat. No. 3,387,394.
The old approaches to multi-sided, segmented, rotating signs have several disadvantages. In order for the signs to properly display the message contained on one side of the segments, all of the segments must be precisely aligned. This requires that the mechanism controlling the position of the segments be precisely controlled. This can be accomplished by using some type of feedback position sensor that precisely controls the drive mechanism. However, this approach can be complex and costly and may require periodic adjustment or maintenance to maintain its proper operation. Therefore, there is a need for a drive mechanism that eliminates the need for such precise control and is simple, inexpensive, and durable.
It is also desirable that the multi-sided segments be held securely in position while displaying each message. Gear and cam driven drive mechanisms often have slop or compliance that increases with wear. If slop or compliance develops in the system, the multiple segments may develop an uneven appearance detracting from the aesthetics and effectiveness of the sign. Therefore, it is desirable that a drive mechanism for a multi-sided, segmented, rotating sign include means to securely hold the segments in a display position between rotational movements.
In traditional multi-sided, segmented, rotating sign assemblies, each of the segments rotates to a new display position at the same time. This creates the appearance of a quick and uniform fade from one advertising message to another. However, for some applications it is desirable that some of the sign segments rotate before other segments so that the appearance of a change sweeping from one portion of the sign to another can be created. Therefore, there is a need for a simple system which allows for sequential rotation of sign segments so as to create enhanced visual effects. However, these enhanced visual effects may only be desirable with certain advertising messages. As different advertising is substituted on the various sides of the multi-sided sign, it may be desirable to change the sequentially changing sign to a traditional uniformly fading sign. Therefore it is desirable that a drive mechanism provide for adjustability so that the same sign can be changed from providing a uniform fade from one message to another to providing a sweeping fade. It is especially desirable that such changes or adjustments be possible in a simple manner for signs that are already installed, such as along a highway.